Cellulose esters and method



UNITED STATES ln i'rsm'r OFFICE CELLULOSE ESTEBS AND METHOD Winfield w. Beckert, Arden, -Del., amignor to E. I. du Pont de Nemours &'Company, Wilmington, Del., a corporation of Delaware No Drawing. Application April 15, 1937,

Serial No. 137,147

9 Ulaims. (Cl. szm This invention relates to cellulosic filaments, widely and depends upon a number of factors, threads, films and fabrics which have increased including thercsultdesired, the nature of the elasticity and/or crease-resistance and to proccellulosic starting material, and the biiunctional esses for preparing such filaments, threads, iilms reagent used. In practice, as will be seen from and fabrics. the examples which follow', I treat the cellulosic 5 This invention has as an object the preparafabric, etc., with a limited amount of the biiunction of crease-resistant cellulosic filaments, tional reagent (e. g., dianhydride of a dicarbom'lic threads, films and fabrics. A further object is acid) and then limit the amount of the reagent the preparation of cellulosic filaments, threads, substituted in the cellulose nucleus by stopping 10 films and fabrics which have increased elasticity. the reaction when the desired increase in elasii) A still further object is the preparation of crea'seticity has been attained. resistant cellulosic filaments, threads, films and From the above it will be seen that, because of fabrics which. have a substantial degree of elasthe number'of variables involved, it is not posticity. A still further objectis the manufacture 'sible to set forth all possible combinations of of threads which will give knitted fabrics with conditions for success. For the operator skilled 15 greater elasticity. Another object is to improve in the art it will be-sufllcient to explain that the the elasticity of fabrics knitted from viscose cellulosic fiber, fabric, etc., is treated with a rayon. Another object is to render cellulosic small amount of a bifunctional esterification or threads and fabrics insoluble in solvents. Other etheriflcation reagent under conditions known objects will appear hereinafter. to-the art to be suitable for the purpose, and .9

These objects are accomplished by subjecting that the reaction is terminated when the rea cellulosic filament, thread, film or fabric to the quired increase in elasticity has. been attained. action of a bifunctional reagent taken from the The invention will be further illustrated but class consisting of carboxylic acid esteriflcation is not intended to be limited by the following agents and etileriflcation agents. In a more' examples in which the quantities are stated in .5

limited sense they are accomplished by reacting parts by weight.

a bifunctional reagent taken from the class con- Example I sisting of carboxylic acid esteriiication agents and etherification agents until substantial pro g g g g sgg ii g ig fig i s g portions of both functional groups of the bifunc- 98 parts of pyridine and adding 112 parts of tional reagent added have reacted and the prodbemyl chloride The pyridine hymcmoride uct has attained increased crease-resistant and which precipitates is filtered off and the Solution 185m pmperties' diluted to 125 parts with pyridine. The cellulosic In t present application mfimctional thread, film or fabric, such as skeins of viscose agents defined those reagents which react rayon regenerated cellulose films or viscose rayon bifunctionally with cellulose. It is known that hose a activated by soaking m water centrifug certain compounds which are bifunctional in I d t t bu u n with n ing and replacing the water with pyridine. They y 3 are then heated with 12 to 18 parts of the above except when combined with other reaction solution at a temperature of about 70 C. for two 40 ducmgbut Mt analytic these means to three days at which time the flber or fabric 40 being called in the cellulose are will have been found to have combined with ap- Thus, phthalic anhydride ordinarily reacts with proximately r equivalent of sebacic acid per cellulose as a monofunctional reagent to give a glucgse t m The reaction t may be derivative which'is soluble in dilute alkalis, i..e. creased'if higher degree of substitution is deone in which one carboxyl 0f the D c anhysired. Continual agitation of the reaction mixdride is combined with the cellulose, the second ture is desirable in order to secure uniform es-' carboxyl remaining free. If, in addition to the terification. Thus, skeins may be arranged on' phthalic anhydride, an impeller (e. g., benzoyl screen trays in a tank and the reaction mixture chloride) is present in the proportion of two circulated over them by removing the fluid at or more mols benzoyi chloride to one moi phthalic the bottom and pumping it back into the tank at I acid, a dianhydride is formed which is capable the top. At the completion of the reaction time of reacting bifunctionaliy with cellulose to form the skeins, films or hose are washed with alan insoluble derivative. echo! and then scoured with:soap in the usual The amount of bifunctionai reagent to be used manner. Hose are boarded over hosiery forms.

. in, the reaction mixture may. be variedquite' Such treatment will have been found toim- Angle of Equivalents oi sebacic acid/glucose residue crease The angle of crease was measured by winding the thread over a double-edged blade while supporting a 50-grarn weight, holding for thirty minutes, releasing the weight, unwinding the angles, cutting these apart, allowing them to recover for ten minutes, and then measuring the recovered angle with a protractor. Perfect crease-resistance by this method would have been indicated by an angle of crease of 180. If the time of creasing were increased, all of the "angles of crease would have been smaller, or if the time had been shortened they would have been larger.

If these yarns are knitted into fabrics, the fabrics are found to have improved elasticity, i. e., they recover more completely after stretching than do similar fabrics knitted from untreated yarn. Thus, a fabric k'nitted from viscose rayon esteriiled with 0.46 equivalent of sebacic acid had an elastic recovery of 63% when stretched 50% for three minutes at 74% relative humidity. The corresponding viscose rayon fabric had an elastic recovery of 42%. treated-in the above manner show similar improvements in elastic recovery from stretch.

It will be noted that the esterifying power of benzoic acid for cellulose is very low, so that in the above treatment cellulose sebacate is produced almost exclusively. Two mols of benzoyl chloride are used with each moi of sebacic acid so that both carboxyl groups of the sebacic acid combine with the cellulose.

Example If Thirty-one and two-tenths (31.2) parts of succinic acid (0.264 moi) were dissolved in 1100 parts of pyridine. Seventy-four and three-tenths (74.3) parts of benzoyl chloride (0.528 mol) were added slowly, with stirring. The mixture was cooled for several hours, filtered and diluted to 1200 parts with pyridine. In case any water is present it is necessary to use an excess of benzoyl chloride to react with it;

A skein of 450 meters of 150 denier gel viscose rayon (rayon which had never been dried) was dehydrated with pyridine and then placed in a jar with 200 parts of the above reaction mixture.

The jar was placed in an oven at C. on a swinging tray which caused the reaction liquid to be constantly agitated. After eighteen hours the skein was removed and washed thoroughly with warm water and dried. The increase in weight indicated at 0.99 equivalent of succinic acid per glucose residue had combined with the cellulose. Its angle of crease was 122 compared with 99 for an untreated control. It was an entirely different product from that obtained by reacting a similar skein with succinic anhydride. The latter product was very sensitive to moisture, had an extremely poor wet strength and was soluble in dilute alkali. The former was not soluble in dilute alkali and was less water-sensitive than the untreated yarn.

Hose

Example III diluted with 38 parts of pyridine. The reaction was carried out under conditions similar to that described in Example II. The product was found to have combined with 0.31 equivalent of adipic acid per glucose residue. The angle of crease of this sample was compared with 95 for the control.

Example IV A skein of cotton thread was reacted with 1 mol of phthalic anhydride and 1 mol of benzoyl chloride in pyridine for sixty-four hours at 50 C. The sample after washing and drying had an angle of crease of 153 (creased fifteen minutes) compared with 134 for the untreated yarn.

Example V A cellulose acetate thread containing 1.38 mols of combined acetic acid per (36 unit of cellulose was prepared by esterifying 450 meters of 150 dernier gel rayon with 200 parts of 25% acetic anhydride in pyridine for about five hours at 70 C. A solution of sebacic-benzoic anhydride was prepared by dissolvingv 101 parts of sebacic acid in 1100 parts of pyridine, adding 140.5 parts of benzoyl chloride with stirring, cooling, filtering and diluting to 1150 parts with pyridine. The cellulose acetate skein was reacted with 150 parts of this solution for forty hours at 70 C. The skeln was washed with alcohol and water, and dried. Its increase in weight indicated that 0.33 equivalent of sebacic acid had combined with the cellulose. The yarn now had an angle of crease of 141 (creased fifteen minutes) compared with 1 for the corresponding viscose yarn and was insoluble in all solventswhich did not destroy the ester linkages.

Example Vl' One hundred (100) parts of cotton filter cloth are steeped in 50% caustic and then pressed to 500 parts. This is treated with 228 parts of dichlorodiethyl ether in 400 parts of benzene in an autoclave for six hours at C. The product still retains its form and is insoluble in all organic solvents and even cuprammonium solution, and may therefore be used for filtering such solutions.

Various types of cellulosic filaments, threads, films and fabrics may be used as starting materials in accordance with my invention. Thus cellulose acetate, propionate, butyrate, etc., and mixed lower carboxylic acid esters, methyl cellulose, ethyl cellulose, etc., and mixed ethers, cellulose glycollc acid, regenerated cellulose such as viscose rayon and cotton when in the form of filaments, threads, films and fabrics may be treated to produce products having increased creaseresistance' and elasticity and insolubility. In the preferred embodiment of the invention, the threads, fabrics, etc., are treated in accordance with the invention and the end-point of the reaction is carefully controlled to give any desired degree of increased elasticity. The process has particular utility in the treatment of viscose rayon skeins or fabrics with blfunctional esterify- 75 ing agents, and this embodiment represents the most important feature of the invention.

The suitable bifunctional reagents include any etherifyim; agent or any esterifying agent which reacts bifunctionally toward cellulose and preferably such reagents containing two or more carbon atoms. I find that the most eifective type of bifunctional etherifying agent has the functional groupsattached to primary carbon atoms. Polyiunctional .etherification agents containing more than two functional groups may also be used.

but for most purposes are less satisfactory than bifunctional reagents. Among the etherifying agents which may be used are ethylene dichloride,

dichlorodlethyl ether, xylylene dibromide, trimethylene chloride, omega-omegadichlorodipropyl ether, and beta-beta'-dichlorodiethyi sulflde.

Polyfunctional esterifying agents which may be used to advantage include dianhydrides or dichlorides derived from dibasic acids or the equivalent thereto, i. e., dibasic acids with an impeller,

the latter being in amount greater than molar in relation to the dibasic acid. Among. the dibasic acids which may be used in combination with an impeller are succinic, adipic, sebacic, phthalic and octadecamethylene dicarboxylic acid; It will be noted that the agents of this invention result in products havingprimary valence bonds between the nuclei of cellulose and the agent.

This invention is useful in a number of ways,

for instance, in the production of crease-resistant textiles, for improving the elasticity of fabrics such as rayon hose, and for rendering threads and fabrics inert to solvents. The threads and fabrics arenew and have innumerable commercial uses,

Crease-resistant and fabric elasticity are very important properties of textile materials composed of cellulose derivatives; This invention'has the advantage that fabrics having the lust-mentioned properties may be easily and economically obtained. An additional advantage lies in the fact that knitted fabrics which are crease-resistant and have good elastic properties may be easily obtained.

The above examples and description are intended to be illustrative only. Any modification of or variation within the scope of the claims.

I claim:

1. The process of increasing the elasticity of, celluiosic material which comprises reacting a .acting a viscose rayon filament, thread or fabric with a dianhydride of a dibasic carboxylic acid until a substantial increase in crease-resistance .is obtained. 1

4. The process according to claim 1 wherein therefrom which conforms to the Y spirit of the invention is intended to be included the dianhydride results from the reaction of a dicarboxyiic acid and benzoyl chloride.

5. The process according to claim 2 wherein the dianhydride results from the reaction of phthalic acid and benzoyl chloride.

. 6. The process according to claim 2 wherein the dianhydride results from the reaction of adipic acid and benzoyl chloride.

"I. The process according to claim 2 wherein the dianhydride results from the reaction of sehacic acid and benzoyl chloride.

' 8. Cellulose filaments, threads, films and fabrics reacted with a'dianhydride of a dibasic carboxylic acid, said products being characterized by substantialiy increased elasticity and crease-resist- 9. Regenerated cellulose filaments, threads and fabrics reactedwith a dianhydride of a dibasic carboxylic acid, said products being characterized' by substantially increased. elasticity and crease-resistance.

' WINFIELD W. HECKERT.

CERTIFICATE OF CORRECTION.

Patent No. 2,170,024. August 22, 1959.

WINFIELD w. HECKERT.

It is hereby certified that error pp in the printed specification I of the above numbered patent requiring correction as follows: Page 1 first column, line L l, for the word impellers read impellers; page 2 first column, line 65, for "at" read that; and second column, line 5, for "benzoil" read benzoyl; line 51, for "demier" read denier; page 5, first column lines 22 and 26, for "impeller" read impeller; line 58, for "Crease-resistant read Crease-resistance; and second column, line 9, claim 1, for "diahydridee" read dianhydrides; line 5 claim LL, for the claim reference numeral "1. read 2; and that the said Letters Patent should be read t is correction th that the same ma conform to the record of the case in the Patent Qff ice.

Signed and sealed this 26th day of September, A. D. 1959.

Henry Van Arsdele (Seal) Acting Commissioner of Patents. 

